The rich and sunny planet Ursa Minor Beta has the quite peculiar property that most of its surface consists of subtropic coastline. Even more peculiar, on this world it's always Saturday afternoon, just right before the beach bars close. Light City, the only city on Ursa Minor Beta, which can only be reached by plane, is the very place where the editorial offices of The Hitchhiker's Guide to the Galaxy reside. A further anomaly in Light City is that the Lalamatine district, just behind the beach, is the only place on the planet not to enjoy a perpetual Saturday afternoon. Instead it is always early evening, with cooling breezes - this is where the nightclubs are located.

So far there's not been much reason to try reaching anything. If we can narrow down some of those 15 billion to be actually earth-like, where we really could colonize a whole planet I'd say you have reason.

Not only are they out of reach to us, we are probably out of reach to them too. The probabilities of any one outside of our solar system knowing that we exist is very small. Now suppose someone on a planet 1,000 light years away was watching us 1,000 years ago. Now suppose they had sufficient technology to determine that we were an inhabitable world with vast oceans. They would know by the absent of radio energy that we did not possess that technology yet. But knowing it would take 1,000 years for the

Surely you mean 3: the warm Earth-like world we're currently standing on (well, in my case, sitting), plus Mars, plus Venus. Both of which are pretty easy to get at using current technology. Some of the gas giant moons probably count too, but they're a special case as they're not in Sol's habitable zone.

Just because the planet's the right mass and about the right distance from its primary doesn't necessarily mean we'd find it habitable...

Given a population of 200-400 billion stars in the Mikly Way, 7.6% are similar to ours for 15-30 billion stars... 1/3 of which would be 5-10 billion stars purportedly hosting planets capable of supporting life as we know it.

Given a population of 200-400 billion stars in the Mikly Way, 7.6% are similar to ours for 15-30 billion stars...

And, keep in mind, a star doesn't have to be all that similar to ours to host life. A majority of the stars in our galaxy are much smaller than our sun, but most of them also have habitable zones plenty big enough to hold one or more planets (or moons) with earthlike surface conditions.

These smaller stars also have the advantage of longer lifespans. Red dwarf stars born a billion years before

Analogue is the 'correct' spelling to describe something not digital for example.

Analog means "an object, concept or situation which in some way resembles a different situation".

What on earth are you talking about? I'm not British, but I'm pretty sure there's only one spelling, "analogue", and they mean the same thing. If something isn't digital, it's analog(ue), and that means "an object, concept or situation which in some way resembles a different situation". There's no difference. What did you think

Please don't. This is an interesting scientific topic and I would rather not have it threadjacked over some damn holy war, no matter what side of the science/debate/politics/religion/controversy you are on.

If there is a Mod listening, please flag this as off-topic, even if it is a joke.

Some have life. Some have, will have, or have had, intelligent life. On some of those worlds they haven't invented radio yet. On some they abandoned radio a long time ago. On some they will never make it that far. Some have died out long ago, leaving only their remains. Some have yet to evolve. Some are there, right now, but are too far away to be detected. At the scales we're talking about we may never meet anyone else before we go extinct.

"they abandoned radio a long time ago" is interesting. I wonder if that was considered when Fermi first made the observation in 1950 -- that a civilization might only radiate detectable emissions during a small period of its existence. Not because it destroyed itself, but because it's a natural progression for a civilization to switch to lower power and ground based conduits shortly after they discover wireless communication.

It's not that anyone thinks its impossible for life to from under other conditions, but that we do know of one set of conditions that worked. Plus, I always thought habitable meant habitable for humans.

Liquid water is the foundation of a lot of interesting chemistry, and also a good temperature regulator. Life getting by without it would likely have to endure much more significant temperature swings.

As a biochemist, the requirement for liquid water seems somewhat reasonable to me. If you want life, you need a chemistry that supplies a minimum level of complexity - you need information storage, you need thermodynamics that can be balanced quite tightly, and from all our knowledge of chemistry, there is not much room for something like that outside of carbon chemistry in liquid water. I wouldn't categorically rule it out, but it is a pretty good bet.

Sure, it seems reasonable... but the universe is big and vast and complex and sneaky.

Essentially, we can only restrict ourselves to what we know. We can't rule out the possibility of some of this stuff, but we can't seriously consider it because it's basically science fiction since we have nothing to suggest it. So, from a science perspective, the answer is to ignore it.

If you can have a cloud of alcohol [universetoday.com] in space, and all of the other wacky stuff we see... I'd be reluctant to be the one to say "you simp

As I said, I would not categorically rule it out. But we know a lot of chemistry outside of biochemistry defining life here, and most of those chemistries do not really support complexity. I am open to be surprised and would be glad to, but I would not bet my house on it.

Huh? There are no living things on Earth that we are aware of that can exist in a living state without water. I'm not sure what you mean by 'think small', as even virii (who's life status is arguable) are inert bits of junk without water.

Why do we still put a mandate of "liquid water" in the hospitable zone requirement?

It's not a "mandate", but it's a way of identifying the first and most likely places to look, for two reasons:

1) Water is necessary for "life as we know it", and we have a good idea of some indicators of life-as-we-know-it that we could observe at a great distance. We have no clue how to recognise life-as-we-DON'T-know-it from a great distance, we just don't know what to look for.

2) There is actually good reason to think that there is a high probability that alien life might be based on the same chemistry

By "hospitable zone requirement" do they mean hospitable for life in general, or hospitable for humans? If life in general then that's ridiculous, of course life can form without water. If hospitable for humans, then I'd think water would be a pretty important thing to have.

No, they mean 'hospitable' for carbon based life-as-we-know-it. It doesn't have to have air conditioning or WIFI and thus may not be habitable for humans.

Unfortunately, all of the democratic and republican presidents have publicly admitted to holding some irrational, religious belief or another. Is there a single, serious, declared atheist candidate? No? Then if we're going to elect another idiot who believes an imaginary friend is telling him to invade other countries, we might as well skip the mainstream irrational and go for the full-on, batshit crazy stuff.

I think that's part of the problem with Christianity: the Bible, and many Christians who believe the whole thing. Jesus never said the Bible was inerrant or true, in fact it didn't exist until long after he died (though the OT parts did).

Here's my suggestion: ignore the Old Testament for the most part, as that's all Jewish stuff. Just read the stuff Jesus himself said and did, and don't worry too much about the rest. I don't even think he's the same as the OT god; he just didn't want to upset people too

Language changes, even reading a couple of hundred year old English work can lead to misunderstanding. For example if someone wrote that Jesus was a nice person, what did they mean?Today it would be a complement, some time ago it may have been an insult or complement and further back it definitely would have been an insult as nice has evolved from meaning silly to fussy to dainty to precise to kind. I'd guess that Greek, Aramaic and Hebrew have had similar changes with the added bonus with Hebrew that they

You're a rational Christian, then? When was the last time you sat down, weighed the factual evidence (not scripture), critically evaluated your beliefs and adjusted them to reflect your perceived probability of your prior beliefs being correct?
I doubt most people who consider themselves religious would even know how to do that. And those that are rational in other areas of their life are obviously not applying rationality to their religious beliefs. So yes, I think labelling religious people as irrational

> When was the last time you sat down, weighed the factual evidence (not scripture), critically evaluated your beliefs and adjusted them to reflect your perceived probability of your prior beliefs being correct?

Quite often I think.You will find, that dealing with scripture in the way religious people do, is not always real. Dealing with scripture generally is not something, my kind is very good at. I am a skeptic. But knowledge about that too slowly accumulates, along with myriads of sideknowledge.So whi

It's easier to disprove, however. I.e. there's more archaeological evidence clearly showing it to be false. Christians dodge the bullet wrt Great Flood etc by claiming that it's all allegorical, but, last I checked, it's not an option for Mormons, at least not for those parts of their scripture that are directly affected. So their only choice is to dismiss the science that proves them wrong as invalid.

A literal reading of the Bible is very clear that world is the entirety of creation, and Noah and whoever was on the Ark were the only survivors. Anything beyond that is creative reinterpretation of the text.

A literal reading of the English translation by a modern westerner is not the same as a literal reading of the ancient Hebrew by an ancient Jew. Hell, there are idioms in the Torah that we still don't know the meaning of.

About 12K years ago, the last ice age ended and sea levels rose, filling a bunch of previously-habitable land up with water. Some of that is believed to have happened very quickly, as ice dams broke in the vicinity of Gibraltar and/or the Bosporus (incidentally, near the areas where the ancestors of the Hebrews lived). You don't think it's reasonable for a group of people living in, say, what is now the middle of the Adriatic Sea to think their entirety of creation (i.e., the few tens of miles or so in any

You don't think it's reasonable for a group of people living in, say, what is now the middle of the Adriatic Sea to think their entirety of creation (i.e., the few tens of miles or so in any direction that they might have been expected to have explored on foot) was flooded?

It's not. The problem is that Bible has God directly address Noah, and claim that he's going to wipe humanity out entirely. If you treat Bible as the literal word of God, there's no way about it. If you treat it as a collection of garbled ancient stories mixed up with myths and legends of ancient Jews, then sure, it makes sense - but not so much as a holy book.

if you listen to the Mormons, they say that the developers talk to us all the time.

What the developers have to say is all there in the manual [biblegateway.com]. Or at least it's supposed to be. Mormons think there are a bunch of other manuals, and Catholics add a few chapters, but other followers of Christ are under the impression that those manuals are uninspired and misleading.

Any civilization smart enough and advanced enough to travel to far-away star systems probably comes to the conclusion that interfering with a non-spacefaring species' development is a bad idea, and develops a Prime Directive forbidding it, and only allowing observation.

It's also possible that one or a group of civilizations this wise have also decided to intercede in case a civilization that's not as wise develops interstellar travel technology and tries to break the Directive.

Like any civilization smart enough and advanced enough to travel to lands half a world away probably comes to the conclusion that interfering with more primitive civilizations' development is a bad idea?

Building a wooden boat and crossing an ocean isn't much of a feat technologically. And I don't see how the Europeans interfering with the pre-Columbian civilizations helped out those civilizations any. It was good for the Europeans, but the natives got screwed.

As for examples, that would be pretty hard considering we don't know any advanced civilizations to ask about the subject (and no, we aren't advanced, we're primitive and barbaric).

And visiting other star systems may be nothing compared to technologies we have not even imagined yet. My point is that there's little reason to assume that the mere acquisition of some technology is going to bring with it a better sense of morality... in fact, if humans are any indication of the general trend for life in the cosmos - just the opposite would be true.

Unless hyperlight travel is actually possible, maybe they don't travel because nobody wants to be away from their home system for decades (or centuries) on a very expensive trip to visit some primitives.

If you have simulation technology that's sophisticated enough, you don't have to physically visit another world in order to experience it. Maybe you send probes, model the world, and then visit it whenever you want from the comfort of your own living room. So, maybe advanced civilizations are visiting us -

Even if there are no higher physics that can shortcut light speed, they should be here by now.

Why? Even at a significant fraction of the speed of light it's going to take a long, long time to colonize the galaxy. Perhaps less than a million years if you are actively trying to colonize the galaxy as fast as possible. If you're doing it on an as-needed basis, it's going to take a lot longer.

There are hundreds of billions of stars. Even visiting them all in some capacity (e.g. Von Neumann probes) would take a

I know we look at planets like ours- becuase we know how to look for life similar to ours as oppossed to other theoretical life forms. BUT- odds are- there are probably a thousand life forms that don't appear anything like earth-forms for every one that does.

There could be life on the sun. The atmopsheric storms of Jupiter might form intelligent life. It's all neat SF, but completely useless to talk about in science. It's not that planetary scientists don't get this, it just that it adds nothing to the conversation to say "life mght be everywhere". Fine, sure, but then what? Beyond SETI, there's no way to detect life-not-as-we-know-it, so it doesn't matter in any practical way.

1) We will have the technology to inhabit "unihabital planets" long before we have the technology to REACH goldilock planets.

Yes, but who really wants to live in a giant artificial dome? It'd be nice to find someplace that's like our own planet naturally.

Anyway, yes, the plan is to find life, and hopefully intelligent life. You're not going to find that on Jupiter or Venus, or at least it's highly unlikely because those planets won't support carbon-and-water-based life like us. To find life that resemble

If there are aliens, how would we know? It's not like we've put much effort into going out and looking for them. All we've done is sit around with some radio telescopes and listen for them, as if they would use something as quaint as radio waves to communicate, and as if the ones about as advanced as us are spending all their energy beaming radio signals into space hoping for someone to answer.

Basically, the idea that "there are no aliens" assumes that we're sooooo special that obviously the aliens would

where:N = the number of civilizations in our galaxy with which communication might be possible;andR* = the average rate of star formation per year in our galaxyfp = the fraction of those stars that have planetsne = the average number of planets that can potentially support life per star that has planetsfl = the fraction of the above that actually go on to develop life at some pointfi = the fraction of the above that actuall

That's the whole problem with this. The Drake Equation is really nothing more than conjecture, and most of the terms are unknown and probably just plain unknowable (unless you're Q). We might be able to get some values for these terms that are somewhat plausible, but only if we actually start exploring other star systems, so that we could start applying some statistics (e.g., "out of 10 star systems we've explored, all 10 had planets, 8 had planets that could potentially support life, 7 have developed lif

The Drake Equation isn't "conjecture" - it's just a way to formulate the question. The numbers you plug into it are largely conjecture at the moment, although we're about to have pretty specific values for many of the elements. This puts some bounds on the final number. The more certain you are regarding each element of the equation, the more tightly bound the final number becomes.